Nearly one third of people over age 65 have hearing loss associated with environmental and genetic factors. Environmental causes include exposure to loud noises, such as industrial machines. Researchers from Indiana University are a step closer to identifying the gene linked to hearing loss as we age.

In a study published by the Journal of the American Medical Association, co-author Terry Reed says scientists analyzed 400 genetic markers in 50 sets of elderly fraternal male twins who reported hearing loss. "You look for markers that are shared more commonly than you would expect."

And that's what researchers found. Reed says the results suggest that this might be the place on the chromosome responsible for hearing loss in the general population. He says the same location was identified in a 2001 German study of progressive hereditary deafness. "This was a form of deafness that the onset occurred in the teen years and later and gradually got worse," he says. "It started out with high tone hearing loss and [there were] a lot of parallels to the hearing loss with age."

Reed says the results - if confirmed - suggest that age-related loss and early onset loss may be on the same gene, but adds that much more research remains to be done to determine whether the two are linked.